What does “good moral character” as a permanent resident mean?

This requirement applies when you apply for naturalization (citizenship), generally in four years and nine months after the grant of your conditional permanent residence.

Do not commit any crime.

Generally speaking the "moral character" issues is only violated if you have arrests or other negative behavior. Otherwise, it does not require an affirmative response or evidence.

The USCIS defines "good moral character" as that "which measures up to the standards of average citizens of the community in which the applicant resides." Because an affirmative showing of "good" moral character has wider interpretation, the USCIS relies on the lack of criminal conduct or questionable conduct to demonstrate "good moral character." Generally, if there are no records of felonious conduct, or criminal activity, or false testimony for the purpose of obtaining citizenship, an applicant is likely to pass.

Good moral character means that up have not been arrested of convicted of any crimes. A conviction may be a ground of inadmissibility.

Without getting into a question regarding moral theology, I believe if you show that you are not and have not been engaged in illegal activities, that should suffice. A police report showing no record and affidavits from friends and neighbors who have known you for a few years should do it.

Good moral character is a requirement for naturalization to become a U.S. citizen and for some forms of relief in immigration removal proceedings. It is not generally a requirement to maintain lawful permanent resident status. Good moral character might be violated by the conviction of a crime or other bad behavior such as lying in order to obtain an immigration benefit or admitting to a crime for which you have not been arrested. In most cases, violating good moral character means that you committed some sort of illegal activity.

It means do not get arrested and pay your taxes. Preferably, do not get arrested for anything, but technically, they are talking about "crimes of moral turpitude" like fraud, anything related to drugs, and the like. Better to just not get arrested and pay your taxes on time.

Generally, it means that you have no criminal history, no arrests, no fights, no domestic violence, no record of any bad behavior. If you do not have anything like that, you do not need to worry about this provision.